A pterosaur egg, MHIN-UNSL-GEO-v246, was discovered in the
Lagarcito Formation in Argentina. This formation is well known for the
Pterodaustro fossils and this egg was clearly a Pterodaustro egg. The embryo was
intact and articulated.

The egg was from the Early Cretaceous deposits about 100 million
years ago, and the proportions of the embryo closely matched those of known
juvenile specimens. Measurements of the shell indicated a very thin (30μm)
leathery shell which was long and oval in shape measuring 22mm by 66mm. The
estimated embryo wingspan was 27cm. This egg has many differences from the
Chinese finds earlier in the same year, but it does support the idea that all
pterosaurs probably laid eggs.